There is a common misconception that ancient people were not smart, or talented.They are just like people today, they have a problem to solve they will invent a method to solve it.Many of the scientific advancements happened by accident. Finding the some rocks melt and create a shiny strong metal, once they found out metal, they rather quickly put it to use.Before that they mixed hide wood and stone to make many tools that are rather useful.The biggest advancements were due to rises of large cultures and cities, that allowed people to obtain time, and resources to make grander things. However it, isn't that the ancient people were too stupid to not building a grand building, but they weren't in a large enough culture to have resources shared to give them free time to go and create such a device. A well would probably take days or weeks of digging, and reinforcing, it probably took a coordinated effort where the labors were to get some extra food for their work, that they didn't hunt themselves, or they choose to do a little less hunting every day and sacrificed to make a well that will give them constant water supply.